On 20/06/2017 at 22:15:36 +0100, Russell King - ARM Linux wrote:

On Tue, Jun 20, 2017 at 05:07:46PM +0200, Benjamin Gaignard wrote:

quoted

2017-06-20 15:48 GMT+02:00 Alexandre Belloni
[off-list ref]:

quoted

quoted

Yes, that's argument against changing rtc _drivers_ for hardware that
can not do better than 32bit. For generic code (such as 44/51 sysfs,
51/51 suspend test), the change still makes sense.

What I had in mind when writing those patches was to remove the limitations
coming from those functions usage, even more since they been marked has
deprecated.

I'd say that they should not be marked as deprecated.  They're entirely
appropriate for use with hardware that only supports a 32-bit
representation of time.

It's entirely reasonable to fix the ones that use other representations
that exceed that, but for those which do not, we need to keep using the
32-bit versions.  Doing so actually gives us _more_ flexibility in the
future.

Consider that at the moment, we define the 32-bit RTC representation to
start at a well known epoch.  We _could_ decide that when it wraps to
0x80000000 seconds, we'll define the lower 0x40000000 seconds to mean
dates in the future - and keep rolling that forward each time we cross
another 0x40000000 seconds.  Unless someone invents a real time machine,
we shouldn't need to set a modern RTC back to 1970.

I agree with that but not the android guys. They seem to mandate an RTC
that can store time from 01/01/1970. I don't know much more than that
because they never cared to explain why that was actually necessary
(apart from a laconic "this will result in a bad user experience")

I think tglx had a plan for offsetting the time at some point so 32-bit
platform can pass 2038 properly.
My opinion is that as long as userspace is not ready to handle those
dates, it doesn't really matter because it is quite unlikely that
anything will be able to continue running anyway.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

-- 
You received this message because you are subscribed to "rtc-linux".
Membership options at http://groups.google.com/group/rtc-linux .
Please read http://groups.google.com/group/rtc-linux/web/checklist
before submitting a driver.
--- 
You received this message because you are subscribed to the Google Groups "rtc-linux" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rtc-linux+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit https://groups.google.com/d/optout.